The hypothesis to be tested is that transfusion of autologous placental/cord blood at birth will benefit preterm infants both sort- term, due to blood volume expansion and to the red blood cells (RBCs) infused, and long-term due to hematopoietic/immunologic progenitor cells (HIPC) infused. Many premature infants are born with a low RBC volume that is sometimes inapparent because the blood hematocrit can be falsely elevated by plasma volume under constriction. The consequent insufficient filing of the systemic and pulmonary vasculature impairs tissue perfusion and oxygenation and leads to RBC transfusions- particularly during the first hours and days of life. At the moment of birth, about 67% of fetal-placental blood is located within the infant's vasculature, compared to 80% when umbilical cord clamping is delayed until 60 seconds post-delivery. Current obstetrical practice is to clamp the umbilical cord immediately following delivery to prevent over- transfusion of term neonates and to permit prompt resuscitation of distressed neonates. Immediate cord clamping denies neonates the potential benefits of an autologous transfusion of RBCs and HIPC. Three specific hypotheses will be tested: 1) transfusion of autologous placental blood and RBCs will increase neonatal circulating blood volume and RBC volume and will improve cardiovascular hemodynamics to provide clinical benefit; and 3) transfusion of autologous HIPC will enhance hematologic development. These hypothesis will be tested by performing a randomized clinical study of preterm neonates, in which the results of relevant laboratory studies and clinical outcomes will be compared between control infants with standard immediate clamping (< 15 seconds) of the umbilical cord versus test infants--the latter divided into two groups depending on gestational age, with either 60 seconds delayed clamping of the cord (larger infants) of immediate clamping followed by resuscitation (smaller infants) and subsequent transfusion (within 24 hours) of autologous following delayed clamping of the umbilical cord will be collected and studies performed to assess its suitability for either later autologous RBC transfusion or HIPC banking and transplantation. These goals will be achieved by the collaborative efforts of investigators with expertise in pediatric hematology and transfusion medicine, neonatology, biochemistry and biostatistics.